Motor control apparatus

A motor control apparatus comprising a control processing unit for creating a motor drive command based on an input signal, a plurality of power supply processing units for supplying a driving voltage to a motor based on said motor drive command, and a signal relay processing unit for supplying said motor drive command received from said control processing unit to said plurality of power supply processing units in a parallel fashion, wherein said control processing unit transmits a preparation request flag enabled state to said plurality of power supply processing units via said signal relay processing unit in order to instruct said plurality of power supply processing units to start preparation for driving said motor, said signal relay processing unit includes a preparation complete flag register for storing preparation complete flags each transmitted from each of said plurality of power supply processing units to indicate the completion of preparation for supplying power to said motor, and transmits a preparation complete flag enabled state to said control processing unit if it can be determined from the contents of said preparation complete flag register that the preparation is completed in all of said plurality of power supply processing units, and said control processing unit transmits a preparation request flag disabled state if said control processing unit does not receive said preparation complete flag enabled state from said signal relay processing unit within a predefined time after transmitting said preparation request flag enabled state, and wherein

• upon receiving said preparation request flag disabled state from said control processing unit, said signal relay processing unit stops transmission of said preparation request flag disabled state to said plurality of power supply processing units, and thereby holds the contents of said preparation complete flag register in a state that existed just before the reception of said preparation request flag disabled state.